Non-Owning References (v1)

I asked on our ADUG forum : "Someone please show me a nicer way than this to create non-owning method references …"

{$APPTYPE CONSOLE}


          program Project_Non_owning_ref;
          uses
            system.SysUtils;
          
          function make_non_owning(const [ref] c:TObject; const m:Tproc):TProc;
            begin
               var _c := @c;
               result := procedure begin
                                      var x := TObject(Pointer(_c)^);
                                      if  x <> nil then m()
                                                   else writeln('dead call')
                                   end
            end;
          
          type
            TMyClass = class
                field : integer;
                procedure   read;
                procedure   incr;
                constructor create;
            end;
          
            procedure   TMyClass.read;    begin   writeln(field);    end;
            procedure   TMyClass.incr;    begin   inc(field);        end;
            constructor TMyClass.create;  begin   field := 42;       end;
          
          begin
            var c   := TMyClass.create;
            var fn1 := make_non_owning(c,c.incr);
            var fn2 := make_non_owning(c,c.read);
          
                c.incr;   c.read;
                c.incr;   c.read;
                fn1();
                fn2();
                //c.free;
                freeandnil(c);
                fn1();
                fn2();
          
                readln;
          end.
          

Output :
• 43
• 44
• 45
• dead call
• dead call

Non-owning References